JANEWAY: Gentlemen, welcome aboard Voyager.
KIM: Thank you, sir.
JANEWAY: Mister Kim, at ease before you sprain something. Ensign, despite Starfleet protocol, I don't like being addressed as sir.
KIM: I'm sorry, ma'am.
JANEWAY: Ma'am is acceptable in a crunch, but I prefer Captain.
The thing about this scene is that after this "at ease before you sprain something" it isn't long before the management theme completely switches to "OMG I better have a tight ship and everything by the book or we'll never get home!!"